Adjustable wrench



May 12, 1931. H. DORN ADJUSTABLE WRENCH 2 Sheets-Sheet 1 Filed July 18, 1927 %porn Earl/IVAN? May 12, 1931. l- LDORN ADJUSTABLE WRENCH Filed Jul 18. 1927 2 Sheets- Sheet 2 lnventaz Patented May 12, 1931 UNITED STATES HANS DORN, F BERLIN, GERMANY ADJUSTABLE WRENCH Application filed July 18, 1927, Serial No.

o my invention to provide means for overcoming it.

I provide a cam as the short arm of, the double armed handle and term the effective length of the cam the distance from the fulcrum of the handle on the head of the wrench to the line along which the short arm of the handle transmits power to the movable jaw. This line, the line of engagement, is therefore the locus of the points in which the cam engages the movable jaw.

A wrench of the kind described will not slip on the medium and small sizes of nuts within its range, if the effective length of the cam is less than the smallest gap within the range from smallest to medium gap.

The aforesaid locus is preferably a straight line parallel to the movement of the jaw and at right angles to the face where the handle contacts with the-jaw. In this manner the force' applied by the handle is utilized in that direction of the movement of the movable jaw in which it is required, and otherwise lateral components will form and generate friction by which the range of adj ustability is reduced.

In the accompanying drawings, a. wrench embod ing my invention is illustrated by way 0 example.

Fig. 1 is an elevation of the wrench with its jaws set for the smallest nut within its range, t

Fig. 2,is a section on the line 2-2 in Fig. 1,

Fig. 3 is a diagram illustrating the proportions of the cam,

Figs. 4 and 5 show the wrench set for a medium and for the largest nut within its range, respectively.

Figs. 6 and 7 are dia rams showing my wrench as compared wit a wrench of the old type.

206,670, and in Germany July 31, 1926.

Referring now to the drawings,1isthehead of the wrench, 2 is its movable and 1 is its fixed jaw, 3 is the handle which is fulcrumed about a pin 5 in the head, 4 is a cam on the handle 3, 2 is a guiding strip on the movable jaw 2, 1. 1" are side plates at the head 1 which enclose the guiding strip 2', and in which the pin 5 is secured, 6, 6 are straightedges or jibs along which the movable jaw is guided in a straight line, 7 is a notch in the guide strip 2 in which the cam 4 engages.

The faces of the cam 4 are curved on evolvcuts, as bent seen in Fig. 3, such evolvents 4' being such that the locus 11 upon turning the handle 3 about its pin 5 becomes a' straight line in parallel to the line in which the movable jaw 2 is reciprocating.

12, Fig. 3 is the effective length referred to in the introduction, being the distance from the locus 11 to the axis of the pin 5. 13, Fig. 1, is the radius of the circle circumscribed to the smallest nut.

The smallest width of gap is'the lower limit of the range of a given wrench. This gap, and the corresponding smallest nut of the range, may be selected as desired but must be not smaller than the limit set by the above condition. It makes no diflerence with respect to the smallest width whether the entire angle through which the handle 3 may be turned, is utilized or not, that is, whether the handle may be turned so far that one of the faces of the cam 4, for opening the wrench, and the opposite face, for closing the wrench, just engages the locus 11, or whether the turning of the handle 3 is limited before it attains the corresponding position.

Referring now to Figs. 6 and 7, 15 is the outline of an old wrench which is shown in heavy lines, and 16 is the outline of my novel wrench which is shown in light lines, both wrenches having identical smallest and medium gaps s and m, respectively. 17, 18 is the axis, to wit, the line which extends through the centre of the head, of an old wrench and of my novel wrench which may intersect the axis of the pin 5 and may be at right angles to the direction in which. the

movable jaw 2 is displaced. Both wrenches are shown at medium gap in Fig. 6 and at smallest gap in Fig. 7. The head of the old wrench is too broad and the guiding strip 2' in Fig. 7 projects too far from the head, so 5 that the wrench is obstructed when it isdesired to operate a nut with the smallest gap. By cutting away the parts, that interfere the nut engaging face of the-fixed jaw would not be brought nearer to the axis 17 18, Figs. 6 and 7.

In my novel wrench the width of the head 'is reduced, and projecting of any parts beyond the outer faces of the two jaws is prevented by bringing nearerthe nut engaging face of the fixed jaw to the axis .17, 18, that is by arranging the axis of medium gap m in eccentric relation to the axis 17 18 of the wrench, and by arranging the notch 7 in eccentric relation to the len h f of the movable jaw and its guiding str1p in the following manner. I

It will appear from Fig. 6 that the axis 19, 20 of the medium gap m of my wrench is pitched away from the axis 17, 18 forthe distance a while the axis of the medium gap m in the old wrench coincides with the wrench axis 17, 18. 1

In the position illustrated in Fig. 6 the axis of the cam 4 in the old and in my novel wrench coincides with the wrench axis 17 18 but in my novel wrench the notch 7 is eccentric with respect to the length I) of the guidin strip 2', the length I) being divided into a onger section 0 and a shorter section d. The length I; of the guiding strip isequal to the breadth f ofthe head in my novel wrench. The breadth of the head is e in the old wrench. e is equal to the medium gap m plus twice the thickness g of the jaws 1 and 2, as appears from Fig. 6. The breadth f is equal to the smallest gap 8 plus twice the thickness g, as appears from Fig. 7.

The medium gap m minus the smallest gap 8 is equal to h, that is, h is equal to half 45 the stroke of the movable jaw. .The breadth f of the head in my novel wrench is smaller than the breadth e of the head in the old wrench for the medium gap m minus the smallest gap 8, that is for &7 at the left and 5 for 71. at the right, as appears from Figs.

6 and 7.

At smallest gap as shown in Fig. 7, the head of the old wrench projects beyond the curved outer face of the movable jaw 2 for the distance 7:. at the left, and the guiding strip 2 projects forthe same distance 72. for the curved outer face of'the fixed jaw 1' at the right. Therefore, while in the old wrench the overall breadth i is equal to 6 9 plus it at smallest gap, in my. novel wrench the overall breadth at smallest gap is f again, the same as in Fig. 6. The overall breadth f of my novel wrench atsmallest gap is still equal to the breadth of the header 5,

right), or minus 2h, or minus the full stroke of the movable jaw 52.

My novel wrench is never broader than the nut engaged, plus the said breadth 2g of the two jaws.

8 is a spiral spring on the pin 5. 8 is the inner end of the spring 8 by which it is directly attached to the handle 3, and 8" is the outer end by which it is directly attached to the head 1 by a slot of the head. The spring tends to pull the parts into the position shown in Fig. 1 that is, to reduce the gap to the'minimum. 9 is the recess in the handle for the reception of the spring 8.

In order to apply the wrench to a nut its head 1 is turned with respect to the handle 3 in the direction of the arrov 14, Fig. 1, and the movable jaw 2 will thereby be moved into the position in Fig. 4;. The spring 8' holds the movable jaw 2 engaged with the nut. By turning the handle 3 as indicated by the arrow 15, Fig. 4, the nut is set while the cam 4 holds the movable jaw 2 firmly on to the nut.

To unscrew a nut, the wrench is applied in reversed position. Fig. 5 shows the position of parts for the widest gap of the wrench.

I claim:

1. An adjustable wrench comprising a head, a fixed jaw on said head, a movable jaw, a handle fulcrumed on said fixed jaw, a spiral spring arranged in a recess of said handle so as to surround the pin on which saidhandle is fulcrumed, its inner end being attached directly to said handle and its outer end directly to said head, a cam on said handle, the perimeter of said recess extending substantially through the point where said cam adjoins said handle, and means for fitting and imparting initial tension to said spring comprising a slot extending from the outer edge of said head to said recess and adapted to receive one end of said spring.

2. An adjustable wrench comprising a head, a fixed jaw on said head, a movable jaw, a handle fulcrumed on said fixed jaw, a spiral spring arranged in a recess of saidhandle so as to surround the pin on which said handle is fulcrumed, its inner end being attached directly to said handle and its outer end directly to said head, a cam on said handle, the perimeter of said recess extending through the point Where said cam adjoins said handle, and means for fitting and imparting initial tension to said spring comprisin a slot extending from the outer edge of sai head to said recess and adapted to receive one end of said spring.

3.An adjustable wrench comprising a head, a fixed jaw onsaid head, a. movable jaw fitted to slide in said head, a doublearmed handle fulcrumed directly to said,

head, a camconstituting the shorter arm of J said handle and adapted to transmit power minus (JAIL a a e left plus 1 a, the; wan mmm aw, the e'fiective le igthjofg said cam being less than the smallest gap within the range from smallest to medium gap.

4. An adjustable wrench comprising a head, a fixed jaw on said head, a movable jaw fitted to slide in said head, a doublearmed' handle fulcrumed directly to said head, a cam constituting the shorter arm of said handle and adapted to transmit power to said movable jaw, the effective length of said cam being less than the smallest gap within the range from smallest to medium gap, and the line along which said cam transmits power to said movable jaw, extending in parallel relation to the direction in which said movable jaw is displaced.

5. An adjustable wrench comprising a head, a fixedijaw on said head, a movable jaw fitted to slide in said head with a guiding strip, a double-armed handle fulcru med di rectly to said head and adapted to transmit power to said movable jaw by its shorterarm, the parts of said wrench beingso designed and arranged with respect to each other that in the position of'the jaws corresponding to the medium gap in the axis of said medium gap is eccentric in the opening direction'of said movable jaw with respect to the axis which extends through the centre of said head, and that in the position of the jaws corresponding to the smallest gap the pitch of the effective faces in said guiding strip which are engaged by said shorter arm, is'

eccentric in the closing direction of said llrliotziable aw with respect to the width of said 6. An adjustable wrench comprising a head, a fixed jaw on said .head, a movable jaw fitted to slide in'said head with a guiding strip, a double-armed handle fulcrumed directly to said head and adapted to transmit power to said movable jaw by its shorter arm, the parts of said wrench being so designed and arranged with respect toeach other that in the position of the jaws corresponding to the medium gap the axis of said medium gap is eccentric in the opening direction of said movable jaw with respectto the axis which extends through the centre of said head, and that-in the position of the jaws corresponding to the smallest gap the pitch of the effective faces in said guiding strip which areengaged by said shorter arm, is eccentric in the closing direction of said movable jaw with respect to the width of said head, and the movable jaw and itsguiding strip being so designed with respect to the outline of the head of said wrench as to be within said outline in the position corresponding to the smallest gap.

In testimony whereof, I fix my signa- I ture.

' HANS DORN. 

